Finding the Net Electric Force on a Charge

1. The problem statement, all variables and given/known data
Three positive point charges are arranged in a triangular pattern in a plane, as shown below.
The Coulomb constant is [tex]8.98755*10^9 N · m^2/C^2.[/tex]

Find the magnitude of the net electric force on the 6 nC charge. Answer in units of N.

You made a good start so far. The magnitude of the force on the 6 nC particle due to the other two particles is done correctly. Your next step is wrong.

Do the following: Draw the two force vectors on the 6 nC charge, and then determine their x- and y- components. Now add the components together to get the net force components on the 6 nC charge. Apply the Pythagorean theorem to these components to get the magnitude of the net force.